Reactive halogen from domestic coal burning aggravates winter air pollution

During the winter in the North China Plain, scientists found high concentrations of reactive halogen gases (BrCl, HOBr, Cl2) in the atmosphere which was associated with widespread coal burning in rural areas. Halogen atoms released from BrCl and Cl2 under sunlight significantly increased the oxidative capacity, and has the potential to boost the productions of secondary aerosols – the major components of winter haze in northern China – and the toxic form of mercury.